It is unlikely that diet is the cause. Acne occurs when androgens (hormones) stimulate the sebaceous glands to produce oil. Oil mixes with bacteria on the skin and inflammed acne spots occur.
An effective treatment will therefore target the hormonal imbalance, excess oil or bacteria.
Talk to your doctor about the various treatments available. An oral antibotic such as Oxytetracycline will kill the acne bacteria. An acne gel such as Duac (clindamycin and benzoyl peroxide) will dry up the oil. Female patients will benefit from an anti-androgen contraceptive pill.
If you are female, are these outbreaks associated with your menstrual cycle?